This is a phase-II, randomized, double-blind study of the protease inhibitor indinavir sulfate (IDV) with either the non-nucleoside reverse transcriptase inhibitor DMP-266 or the nucleoside analog 11592U89, or with DMP-266 plus 1592U89 in subjects who have received zidovudine (ZDV) or d4T/3TC?. The study is designed to determine if viral replication can be successfully suppressed with the substitution of potent new agents. Subjects will be randomized to one of the three treatment arms and followed for 48 weeks beyond the enrollment of the last subject. Virologic response will be compared across the study arms with respect to proportion of subjects with plasma HIV RNA levels below the limit of detection (< 200 copies/ml) at Week16 and time to detectable viremia (2 consecutive plasma HIV RNA levels 200 copies/ml). Safety and tolerance of the study arms will also be assessed.